High Knob Overlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the High Knob Overlook clear sky chart from 2005-11-06 to 2024-01-16.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	17% 9% 4 7% 6% 3 5% 5% 5% 7% 33%	74736
	Night	17% 9% 4 6% 5% 3 5% 4 5% 7% 35%	75068
Transparency	Day	50% 7% 11% 19% 11% 1	74446
	Night	49% 7% 12% 20% 11% 1	74892
Seeing	Day	25% 18% 29% 18% 8% 3	13646
	Night	21% 18% 30% 22% 8% 1	23091

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	12% 13% 7% 9% 7% 4 6% 5% 5% 6% 27%	1517
	11th to 20th	Day	17% 14% 6% 12% 8% 4 6% 4 4 6% 22%	1558
	21st to end	Day	12% 17% 7% 10% 9% 3 5% 4 4 6% 23%	1782
February	1st to 10th	Day	17% 14% 6% 8% 7% 4 6% 5% 5% 5% 23%	1620
	11th to 20th	Day	15% 13% 6% 9% 7% 4 5% 5% 4 6% 27%	1605
	21st to end	Day	19% 13% 4 9% 7% 3 4 3 5% 6% 27%	1480
March	1st to 10th	Day	15% 10% 6% 8% 5% 3 5% 3 4 5% 34%	1877
	11th to 20th	Day	16% 12% 6% 8% 6% 3 4 3 5% 6% 31%	1980
	21st to end	Day	19% 12% 4 7% 6% 3 3 4 4 6% 32%	2245
April	1st to 10th	Day	18% 11% 4 8% 5% 3 5% 4 4 6% 33%	2160
	11th to 20th	Day	18% 10% 3 6% 6% 3 4 4 5% 7% 34%	2134
	21st to end	Day	19% 8% 3 5% 5% 4 4 5% 5% 7% 34%	2166
May	1st to 10th	Day	21% 9% 3 6% 6% 3 5% 5% 5% 7% 32%	2407
	11th to 20th	Day	23% 6% 3 6% 6% 4 5% 4 5% 6% 32%	2478
	21st to end	Day	18% 6% 2 5% 5% 3 5% 4 6% 9% 37%	2725
June	1st to 10th	Day	16% 6% 3 5% 7% 4 5% 5% 6% 8% 34%	2520
	11th to 20th	Day	17% 7% 2 6% 6% 3 6% 5% 6% 7% 35%	2520
	21st to end	Day	14% 6% 2 5% 6% 3 6% 6% 7% 9% 37%	2520
July	1st to 10th	Day	11% 5% 3 5% 7% 4 7% 7% 7% 8% 36%	2520
	11th to 20th	Day	10% 5% 3 5% 5% 4 6% 5% 7% 10% 40%	2520
	21st to end	Day	13% 6% 3 6% 6% 4 6% 6% 6% 7% 36%	2658
August	1st to 10th	Day	13% 6% 3 6% 6% 4 6% 5% 6% 9% 35%	2327
	11th to 20th	Day	15% 7% 3 6% 7% 3 5% 6% 7% 9% 33%	2236
	21st to end	Day	16% 5% 2 6% 6% 4 5% 6% 7% 9% 33%	2376
September	1st to 10th	Day	18% 6% 3 5% 5% 3 4 3 4 9% 39%	2160
	11th to 20th	Day	16% 5% 2 5% 5% 3 4 5% 4 6% 46%	2160
	21st to end	Day	21% 7% 3 5% 4 2 4 4 5% 7% 37%	1908
October	1st to 10th	Day	20% 8% 2 5% 4 3 4 5% 5% 7% 38%	1800
	11th to 20th	Day	23% 8% 2 6% 5% 3 4 4 5% 6% 34%	1800
	21st to end	Day	23% 11% 3 6% 6% 3 4 4 5% 6% 29%	1963
November	1st to 10th	Day	15% 9% 3 6% 5% 2 4 5% 5% 6% 40%	1671
	11th to 20th	Day	18% 12% 4 6% 6% 2 5% 4 5% 5% 34%	1625
	21st to end	Day	20% 12% 3 6% 5% 3 4 5% 5% 6% 31%	1520
December	1st to 10th	Day	21% 13% 6% 10% 7% 4 4 4 4 5% 23%	1520
	11th to 20th	Day	22% 13% 5% 6% 4 3 5% 3 4 7% 27%	1906
	21st to end	Day	22% 17% 7% 9% 6% 4 4 4 4 5% 18%	2772
January	1st to 10th	Night	14% 13% 5% 8% 7% 3 6% 4 5% 6% 29%	2649
	11th to 20th	Night	17% 13% 6% 9% 6% 3 4 5% 5% 6% 27%	2530
	21st to end	Night	12% 12% 5% 9% 8% 4 6% 5% 6% 6% 27%	2574
February	1st to 10th	Night	16% 12% 6% 7% 7% 4 5% 5% 5% 6% 28%	2340
	11th to 20th	Night	14% 11% 4 9% 6% 4 6% 5% 5% 6% 29%	2240
	21st to end	Night	17% 12% 4 9% 7% 3 5% 3 5% 5% 29%	1776
March	1st to 10th	Night	15% 9% 4 7% 5% 3 5% 5% 7% 7% 33%	2067
	11th to 20th	Night	17% 10% 3 7% 5% 4 4 5% 4 5% 35%	1979
	21st to end	Night	17% 11% 4 6% 6% 3 5% 4 5% 5% 36%	2110
April	1st to 10th	Night	19% 12% 5% 6% 6% 3 4 4 5% 7% 31%	1800
	11th to 20th	Night	17% 7% 3 5% 5% 3 5% 5% 5% 7% 38%	1775
	21st to end	Night	19% 6% 3 5% 4 3 4 4 5% 6% 39%	1800
May	1st to 10th	Night	23% 10% 2 5% 5% 2 4 3 4 6% 35%	1560
	11th to 20th	Night	17% 5% 2 5% 6% 3 6% 5% 6% 6% 39%	1415
	21st to end	Night	16% 6% 2 5% 5% 3 5% 4 5% 9% 41%	1550
June	1st to 10th	Night	16% 5% 2 5% 5% 3 5% 5% 5% 8% 42%	1440
	11th to 20th	Night	14% 7% 2 5% 5% 4 5% 5% 6% 10% 37%	1440
	21st to end	Night	14% 5% 2 5% 5% 3 4 5% 7% 8% 42%	1440
July	1st to 10th	Night	11% 6% 2 5% 5% 3 5% 5% 6% 8% 43%	1440
	11th to 20th	Night	11% 5% 2 5% 6% 3 4 4 7% 10% 43%	1440
	21st to end	Night	13% 5% 3 6% 5% 3 4 5% 6% 10% 41%	1656
August	1st to 10th	Night	12% 4 2 5% 4 4 5% 6% 6% 8% 42%	1611
	11th to 20th	Night	13% 6% 3 6% 6% 4 5% 4 6% 7% 40%	1647
	21st to end	Night	13% 6% 3 5% 4 3 5% 4 5% 7% 44%	1980
September	1st to 10th	Night	16% 6% 3 5% 5% 3 4 4 4 6% 43%	1800
	11th to 20th	Night	15% 5% 2 5% 4 2 3 3 4 8% 50%	1800
	21st to end	Night	18% 7% 2 5% 4 3 4 4 5% 6% 42%	2048
October	1st to 10th	Night	21% 7% 3 5% 4 2 3 3 4 5% 42%	2160
	11th to 20th	Night	20% 8% 3 5% 5% 3 3 3 4 5% 41%	2160
	21st to end	Night	23% 10% 3 6% 5% 2 4 5% 4 6% 32%	2391
November	1st to 10th	Night	13% 9% 3 5% 5% 2 4 4 5% 7% 43%	2407
	11th to 20th	Night	19% 11% 4 6% 6% 3 4 5% 5% 6% 32%	2551
	21st to end	Night	16% 12% 4 6% 6% 3 4 4 6% 6% 33%	2660
December	1st to 10th	Night	20% 13% 6% 8% 6% 4 5% 4 5% 6% 24%	2660
	11th to 20th	Night	20% 13% 4 8% 7% 4 5% 4 4 5% 27%	3288
	21st to end	Night	23% 14% 6% 7% 6% 3 4 4 5% 6% 21%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	57% 7% 11% 16% 8% 1	1518
	11th to 20th	Day	65% 6% 9% 12% 7% 1	1558
	21st to end	Day	62% 5% 10% 14% 8% 1	1782
February	1st to 10th	Day	62% 6% 10% 13% 8% 1	1620
	11th to 20th	Day	57% 6% 7% 21% 8% 1	1614
	21st to end	Day	58% 6% 7% 19% 8% 2	1480
March	1st to 10th	Day	54% 5% 10% 20% 9% 2	1880
	11th to 20th	Day	54% 4 8% 20% 10% 3	1980
	21st to end	Day	54% 6% 7% 17% 13% 3	2245
April	1st to 10th	Day	52% 6% 9% 20% 11% 3	2160
	11th to 20th	Day	49% 7% 10% 19% 14% 2	2134
	21st to end	Day	48% 7% 9% 19% 13% 3	2166
May	1st to 10th	Day	52% 6% 10% 18% 12% 2	2407
	11th to 20th	Day	52% 7% 9% 19% 11% 2	2482
	21st to end	Day	43% 8% 14% 22% 11% 2	2725
June	1st to 10th	Day	46% 9% 12% 20% 13% 1	2520
	11th to 20th	Day	47% 9% 13% 19% 11% 1	2520
	21st to end	Day	41% 9% 14% 26% 10%	2520
July	1st to 10th	Day	43% 10% 13% 21% 13% 1	2450
	11th to 20th	Day	38% 9% 17% 23% 13% 1	2445
	21st to end	Day	43% 9% 13% 19% 14% 1	2509
August	1st to 10th	Day	44% 9% 15% 21% 11%	2314
	11th to 20th	Day	45% 10% 14% 20% 10% 1	2236
	21st to end	Day	45% 9% 10% 21% 13% 2	2376
September	1st to 10th	Day	44% 6% 12% 22% 14% 2	2160
	11th to 20th	Day	38% 6% 11% 22% 20% 2	2160
	21st to end	Day	46% 6% 11% 19% 16% 2	1908
October	1st to 10th	Day	46% 7% 12% 22% 13% 1	1800
	11th to 20th	Day	50% 7% 9% 24% 10%	1800
	21st to end	Day	56% 6% 12% 16% 9% 1	1963
November	1st to 10th	Day	44% 7% 12% 19% 15% 3	1671
	11th to 20th	Day	52% 7% 11% 18% 11% 2	1625
	21st to end	Day	52% 8% 12% 21% 7% 1	1520
December	1st to 10th	Day	65% 5% 11% 12% 7% 1	1520
	11th to 20th	Day	58% 6% 13% 18% 5%	1906
	21st to end	Day	68% 6% 9% 13% 4	2772
January	1st to 10th	Night	55% 7% 10% 17% 10% 1	2649
	11th to 20th	Night	58% 6% 13% 15% 6% 1	2530
	21st to end	Night	55% 7% 10% 17% 11% 1	2574
February	1st to 10th	Night	56% 7% 10% 18% 8% 1	2340
	11th to 20th	Night	56% 6% 9% 17% 11% 1	2242
	21st to end	Night	56% 5% 9% 18% 11% 2	1776
March	1st to 10th	Night	48% 8% 11% 22% 9% 2	2077
	11th to 20th	Night	50% 7% 11% 19% 12% 1	1980
	21st to end	Night	51% 6% 10% 16% 15% 3	2110
April	1st to 10th	Night	54% 5% 10% 18% 11% 2	1800
	11th to 20th	Night	45% 7% 12% 20% 15% 1	1775
	21st to end	Night	45% 7% 11% 20% 15% 3	1800
May	1st to 10th	Night	51% 6% 10% 21% 10% 3	1560
	11th to 20th	Night	44% 8% 10% 20% 15% 2	1416
	21st to end	Night	41% 9% 15% 20% 13% 3	1551
June	1st to 10th	Night	41% 7% 12% 25% 14% 1	1440
	11th to 20th	Night	41% 9% 14% 25% 10% 2	1440
	21st to end	Night	36% 9% 14% 28% 12% 1	1440
July	1st to 10th	Night	38% 8% 13% 25% 13% 2	1400
	11th to 20th	Night	34% 9% 16% 26% 14% 1	1392
	21st to end	Night	36% 10% 16% 21% 14% 2	1564
August	1st to 10th	Night	36% 9% 17% 26% 12% 1	1600
	11th to 20th	Night	42% 7% 15% 22% 13%	1647
	21st to end	Night	38% 8% 12% 25% 16% 1	1980
September	1st to 10th	Night	42% 7% 10% 25% 14% 2	1800
	11th to 20th	Night	35% 6% 12% 26% 20% 2	1800
	21st to end	Night	42% 5% 11% 24% 17% 1	2048
October	1st to 10th	Night	44% 7% 12% 22% 14% 1	2160
	11th to 20th	Night	45% 6% 13% 24% 11% 2	2160
	21st to end	Night	52% 6% 11% 19% 10% 1	2391
November	1st to 10th	Night	40% 7% 12% 22% 16% 3	2407
	11th to 20th	Night	51% 7% 11% 18% 11% 3	2551
	21st to end	Night	49% 7% 15% 21% 7% 1	2660
December	1st to 10th	Night	60% 8% 11% 16% 6%	2660
	11th to 20th	Night	59% 5% 11% 16% 9%	3288
	21st to end	Night	61% 9% 10% 15% 4	4884

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	31% 27% 31% 9% 1 1	180
	11th to 20th	Day	41% 28% 25% 4	204
	21st to end	Day	27% 32% 31% 8% 3	264
February	1st to 10th	Day	41% 28% 27% 4	240
	11th to 20th	Day	33% 32% 32% 3	272
	21st to end	Day	36% 26% 29% 8%	346
March	1st to 10th	Day	33% 26% 29% 11% 2	420
	11th to 20th	Day	29% 28% 29% 11% 2 1	420
	21st to end	Day	34% 25% 26% 10% 3 2	462
April	1st to 10th	Day	30% 27% 27% 12% 4	420
	11th to 20th	Day	26% 29% 24% 13% 6% 2	412
	21st to end	Day	28% 24% 32% 11% 3 2	420
May	1st to 10th	Day	31% 17% 30% 11% 8% 2	423
	11th to 20th	Day	26% 18% 30% 16% 8% 2	447
	21st to end	Day	21% 14% 27% 20% 14% 4	485
June	1st to 10th	Day	19% 16% 32% 23% 8% 1	450
	11th to 20th	Day	19% 16% 29% 25% 10% 1	450
	21st to end	Day	16% 12% 38% 23% 9% 1	450
July	1st to 10th	Day	14% 8% 28% 30% 15% 4	445
	11th to 20th	Day	10% 7% 31% 33% 14% 5%	444
	21st to end	Day	14% 9% 35% 27% 12% 3	488
August	1st to 10th	Day	13% 9% 26% 29% 18% 5%	446
	11th to 20th	Day	16% 6% 28% 31% 14% 6%	439
	21st to end	Day	17% 9% 28% 26% 12% 8%	495
September	1st to 10th	Day	22% 10% 25% 21% 16% 6%	450
	11th to 20th	Day	14% 10% 29% 22% 17% 7%	450
	21st to end	Day	24% 11% 30% 19% 12% 4	450
October	1st to 10th	Day	27% 11% 24% 22% 12% 4	450
	11th to 20th	Day	26% 16% 35% 16% 6%	450
	21st to end	Day	31% 21% 28% 16% 5%	486
November	1st to 10th	Day	25% 20% 27% 21% 6% 1	365
	11th to 20th	Day	28% 25% 29% 14% 3	285
	21st to end	Day	31% 26% 36% 7% 1	180
December	1st to 10th	Day	35% 30% 24% 7% 3 1	180
	11th to 20th	Day	37% 27% 27% 9%	180
	21st to end	Day	34% 26% 34% 4 2	198
January	1st to 10th	Night	22% 28% 38% 10% 3	760
	11th to 20th	Night	24% 23% 34% 17% 2	744
	21st to end	Night	20% 29% 36% 14% 1	792
February	1st to 10th	Night	25% 26% 36% 12% 1	720
	11th to 20th	Night	24% 29% 37% 9% 1	703
	21st to end	Night	29% 23% 34% 12% 1	592
March	1st to 10th	Night	24% 28% 32% 14% 2	720
	11th to 20th	Night	27% 23% 31% 15% 4	720
	21st to end	Night	24% 24% 34% 12% 6%	792
April	1st to 10th	Night	24% 26% 31% 16% 3	720
	11th to 20th	Night	21% 23% 32% 17% 6%	711
	21st to end	Night	24% 18% 33% 20% 5%	720
May	1st to 10th	Night	28% 14% 24% 25% 10%	480
	11th to 20th	Night	17% 11% 38% 25% 8% 1	354
	21st to end	Night	19% 9% 28% 30% 15% 1	389
June	1st to 10th	Night	16% 8% 27% 36% 13% 1	360
	11th to 20th	Night	16% 8% 27% 37% 13%	360
	21st to end	Night	14% 4 33% 39% 9% 1	360
July	1st to 10th	Night	12% 5% 25% 38% 18% 2	350
	11th to 20th	Night	11% 2 27% 38% 20% 2	348
	21st to end	Night	14% 5% 19% 42% 18% 1	476
August	1st to 10th	Night	12% 2 22% 44% 19% 1	537
	11th to 20th	Night	15% 5% 16% 35% 26% 3	583
	21st to end	Night	13% 6% 22% 36% 20% 3	792
September	1st to 10th	Night	17% 9% 24% 33% 16% 2	720
	11th to 20th	Night	16% 8% 24% 26% 22% 5%	720
	21st to end	Night	20% 11% 24% 27% 16% 3	720
October	1st to 10th	Night	23% 11% 24% 23% 16% 2	720
	11th to 20th	Night	24% 14% 30% 25% 6% 1	720
	21st to end	Night	29% 16% 32% 19% 4	792
November	1st to 10th	Night	17% 19% 34% 23% 7%	740
	11th to 20th	Night	26% 20% 31% 17% 4 1	760
	21st to end	Night	23% 21% 34% 18% 3 1	760
December	1st to 10th	Night	27% 24% 33% 13% 4	760
	11th to 20th	Night	23% 26% 34% 16% 3	760
	21st to end	Night	27% 24% 35% 12% 2	836

Page generated at 2024-01-13 19:28:28. Version ac07

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